Round-3 fixes. Two threads:
- 9 OPEN SonarQube issues caused the "E Security Rating on New Code"
gate failure. The bot's diagnosis (sa.text(text_sql) → SQL injection)
was a wrong guess; the actual SQ rules firing were different.
- Bot's substantive concerns: pool defaults too aggressive,
delete_browser_session RETURNING path untested on Postgres,
schema_version legacy table created on Postgres, stale module
docstring.
- User's underlying question on the pool: "isn't 1 connection enough?"
Right-sized to 2+5 and documented the concurrency model in ADR-026
so the rationale is durable.
SonarQube quality-gate fixes (clears all 9 OPEN issues)
-------------------------------------------------------
- BLOCKER S6418: rename `SECRET` constant in test_storage_logging.py
to `SENTINEL_PASSWORD_FRAGMENT` + NOSONAR with rationale.
- CRITICAL S3776: extract `_build_postgres_engine()` from
`initialize()` (was complexity 26 > 15); incidentally creates a
clean unit-test seam for engine args.
- CRITICAL S4423: `ssl.create_default_context(cafile=...)` is flagged
as "weak protocol" — Python 3.10+ already negotiates the strongest
available protocol. Explicitly pass `purpose=ssl.Purpose.SERVER_AUTH`
and NOSONAR with the Python-version rationale.
- MAJOR S3358: split the TLS-mode nested ternary in the engine
factory into a `_describe_ssl_arg()` helper.
- MAJOR S2068 ×3: bind test app-password literals to local vars and
put `# NOSONAR S2068` on the same line as the literal (anchoring
requirement) instead of on the closing paren.
- MINOR S7503 ×2: `# NOSONAR S7503` on `_Cursor.__aenter__/__aexit__`
— they MUST be `async` per the context-manager protocol.
Pool sizing right-sized (answers "why so many connections?")
------------------------------------------------------------
- `DATABASE_POOL_SIZE` default 10 → **2**.
- `DATABASE_MAX_OVERFLOW` default 20 → **5**.
- Per-pod max drops from 30 to 7. With 3 replicas, total = 21
connections (was 90) — well under managed-Postgres
`max_connections=100`.
- New INFO log at startup: `Postgres engine ready: pool_size=N
max_overflow=M (per-pod max K connections)`. Surfaces the active
sizing without grepping config.
- New ADR-026 § "Concurrency model and pool sizing" explains
asyncpg's single-flight connection semantics, the MCP workload
shape (read-mostly point lookups), why-not-1 (multi-user
serialization), and the tune-up/tune-down recipe.
- `docs/configuration.md` table updated with new defaults +
homelab-vs-prod tuning guidance, linking the ADR.
RETURNING path covered on Postgres
----------------------------------
- New `test_browser_session_delete_returning` exercises the
`DELETE … RETURNING user_id` path — the only RETURNING clause in
the storage layer and the most dialect-sensitive SQL in this PR.
Asserts both present-row (returns True, row gone) and absent-row
(returns False) branches.
Schema portability polish
-------------------------
- `alembic 001`: gate `schema_version` table creation on
`op.get_bind().dialect.name == "sqlite"`. The table exists purely
to match the fingerprint of pre-Alembic SQLite databases; fresh
Postgres installs no longer carry the dead legacy table.
Misc polish
-----------
- Module docstring: "SQLite-based" → "SQL-backed", with a sentence
on the DATABASE_URL opt-in and an ADR-026 link.
- Comment on `_wrap_row` noting `row._mapping` is the documented
RowMapping accessor in SQLAlchemy 2.x despite the underscore.
Skipped (rationale in PR reply)
-------------------------------
- `_qmark_to_named` SQL-comment handling: docstring already notes
the limitation; no `?` in storage SQL comments today.
- Module-level `anyio.Lock()`: established precedent confirmed by
the bot itself.
- `get_audit_logs` `SELECT *`: pre-existing pattern, out of scope.
Verification
------------
- `uv run pytest tests/unit/` — 1025 passed.
- `TEST_DATABASE_URL=… uv run pytest tests/integration/test_storage_postgres.py -m postgres` — 7 passed.
- `ruff check && ruff format --check && ty check` — clean.
- Confirmed `schema_version` absent on fresh Postgres, still present
on fresh SQLite.
Tracked on Astrolabe Cloud POC board, card #99.
---
_This PR was generated with the help of AI, and reviewed by a Human_
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
